Data receiver with symbol rate discrimination and statistical analysis functions

Abstract

A received signal has been converted from a source symbol rate to another symbol rate by symbol repetition, then interleaved to form frames in which the same symbol sequence is repeated multiple times. The source symbol rate is identified by dividing each frame into various numbers of blocks, and determining whether each such division makes at least a certain proportion of the blocks identical. The source symbols are reproduced by identifying a subset of similar blocks from statistical properties of the blocks, and combining the signal values in the subset of blocks.

What is claimed is: 
     
       1. A method of identifying the data rate of a received signal that has been interleaved at a fixed symbol rate to form frames, comprising the steps of: (a) dividing one of said frames into N blocks of equal length, where N is an integer greater than unity;   (b) comparing said N blocks; and   (c) identifying said data rate as being equal to said fixed symbol rate divided by N, if more than a certain proportion of said blocks are mutually identical.   
     
     
       2. The method of claim 1, comprising the further step of: (d) changing N to a different integer greater than unity and repeating said steps (a) to (c), if not more than said certain proportion of said blocks are mutually identical.   
     
     
       3. The method of claim 1, wherein said certain proportion is one-half. 
     
     
       4. The method of claim 1, wherein said steps (a) to (c) are employed to identify data rates in a first set of predetermined data rates. 
     
     
       5. The method of claim 4, comprising the further steps of: (e) processing said received signal at an assumed data rate in a second set of predetermined data rates, thereby obtaining reproduced data;   (f) performing an error check on said reproduced data; and   (g) identifying said data rate as being equal to said assumed data rate, if said error check passes.   
     
     
       6. The method of claim 5, comprising the further step of: (h) repeating said steps (e), (f), and (g) for different assumed data rates in said second set of predetermined data rates, until said data rate is identified in said step (g).   
     
     
       7. The method of claim 5, wherein the data rates in said first set of predetermined data rates are slower than the data rates in said second set of predetermined data rates. 
     
     
       8. A data rate discriminator for identifying the data rate of a received signal that has been interleaved at a fixed symbol rate to form frames, comprising: a buffer for storing at least one of said frames;   a repetition checker coupled to said buffer, for dividing said one of said frames into N blocks of equal length, where N is an integer greater than unity, comparing said N blocks, and reporting information indicating whether more than a certain proportion of said blocks are mutually identical; and   a data rate decision circuit coupled to said repetition checker, for supplying at least one value of N to said repetition checker and determining said data rate according to the information reported by said repetition checker.   
     
     
       9. The data rate discriminator of claim 8, wherein said certain proportion is one-half. 
     
     
       10. The data rate discriminator of claim 8, also comprising a binary decision circuit for assigning a binary value to each symbol in said received signal, wherein said buffer stores the assigned binary value of each symbol in said one of said frames. 
     
     
       11. The data rate discriminator of claim 8, also comprising: a decoding means coupled to said data rate decision circuit, for decoding said received signal at at least one assumed data rate, and issuing reports indicating whether correct decoded data are obtained.   
     
     
       12. The data rate discriminator of claim 11, wherein said data rate decision circuit identifies data rates in a first set of predetermined data rates from the information reported by said repetition checker, and identifies data rates in a second set of predetermined data rates from the reports issued by said decoding means, the data rates in said first set of predetermined data rates being slower than the data rates in said second set of predetermined data rates. 
     
     
       13. The data rate discriminator of claim 11, wherein said decoding means performs a convolutional decoding process. 
     
     
       14. The data rate discriminator of claim 8, wherein said received signal has been transmitted from a base station to a mobile station in a code-division multiple-access communication system. 
     
     
       15. A data receiver for receiving a signal having a variable data rate, after the data have been interleaved to form frames with a fixed number of symbols and transmitted at a fixed symbol rate, comprising: a buffer for storing at least one of said frames;   a repetition checker coupled to said buffer, for dividing said one of said frames into N blocks of equal length, where N is an integer greater than unity, comparing said N blocks, and reporting information indicating whether more than a certain proportion of said blocks are mutually identical;   a data rate decision circuit coupled to said repetition checker, for supplying at least one value of N to said repetition checker and identifying said data rate from the information reported by said repetition checker; and   a decoding means coupled to said data rate decision circuit, for decoding said received signal at the data rate identified by said data rate-decision circuit.   
     
     
       16. The data receiver of claim 15, wherein said certain proportion is one-half. 
     
     
       17. The data receiver of claim 15, also comprising a binary decision circuit for assigning a binary value to each symbol stored in said buffer. 
     
     
       18. The data receiver of claim 15, wherein said decoding means issues reports to said data rate decision circuit, indicating whether correct decoded data are obtained. 
     
     
       19. The data receiver of claim 18, wherein said data rate decision circuit identifies data rates in a first set of predetermined data rates from the information reported by said repetition checker, and identifies data rates in a second set of predetermined data rates by having said decoding means perform trial decoding of said received signal and receiving resulting reports from said decoding means, the data rates in said first set of predetermined data rates being slower than the data rates in said second set of predetermined data rates. 
     
     
       20. The data receiver of claim 15, wherein said decoding means performs a convolutional decoding process. 
     
     
       21. The data rate discriminator of claim 15, wherein said received signal has been transmitted from a base station to a mobile station in a code-division multiple-access communication system.